Some PoS coins boast that you need more than 51% of the coin to control/destroy the normal functioning of the network, but we'll just focus on 51% now.
How much would it cost to buy 51% of BTC (not including lost/unused/unallocated)
Please comment below.
The reason it is 51% of "owned" coins is that in PoS only actively owned/used coins count, so lost/unused coins don't count... at present, i think there are about 10-12million BTC that are "used"... so the question is, how much to buy about 6million btc...although this figure may change if the purchase happens slowly, over a year or two. The cost estimate still stays valid/interesting
51% attack means To own the 51% of hashing power over all not 51% of btc